Anew report published by the thinktank Civitas claims that increasing the length of prison sentences for burglary and fraud reduces offending. But this simple analysis hides a much more complicated problem. According to the Civitas research, increasing the average sentence for burglary by one month would reduce offending by about 0.5%. In our experience at Nacro, all that prison does in these cases is to delay the next offence from taking place. A slightly longer sentence just means a slightly longer delay in reoffending.

We already know from other research that short-term prison sentences don't reduce reoffending, particularly for serious repeat offenders. We also know that the length of custodial sentences has been increasing significantly over the past decade with no causal link to a reduction in reoffending. It concerns me that the findings from this research are being used by some to advocate longer sentences in order to reduce crime. At Nacro, we believe much more can be done to radically reduce crime and make communities safer; to do this, we must get to the root of offending behaviour and stop people reoffending.

We don't argue this to be controversial or because we are on the side of the criminal. We argue this because our sole focus as a charity is to reduce crime and reduce the number of victims of crime. If prison were the answer to high reoffending rates, particularly for acquisitive crime, we would argue for more prisons. But the evidence clearly points us in the opposite direction. Not only are community sentences proven to be 8% more effective than short-term prison sentences at reducing reoffending, but they can also challenge criminal behaviour; they are better at dealing with drug and alcohol problems; they require people to repair the damage caused by their crimes; and they cost significantly less. A study by the National Audit Office in 2010 found that the cost of a six-week stay in prison was £4,500. For an offence such as burglary, a 12-month prison sentence would cost the state more than £40,000. By comparison, an intensive two-year community order with 80 hours of unpaid work and mandatory accredited programmes would cost just £4,200.

When someone is sent to prison they often lose their home and their job, and family and social relationships frequently deteriorate. This can sever any positive ties an offender may have with the law-abiding community, and makes it all the more likely that they'll fall back into a cycle of offending. In many cases, prison does not challenge an individual's behaviour, it does not highlight the damage caused to victims and communities, and it can make matters worse by normalising criminal behaviour and severely affecting an individual's mental and physical health. More than 70% of male prisoners suffer from two or more mental disorders, two-thirds of male prisoners have a reading age of 11 or lower, and more than a third of the prison population have committed 15 or more offences. Put simply, prison is not the right place to rehabilitate the vast majority of offenders.

To think that simply locking people up for longer will make any difference is to ignore reality. As a former governor of Brixton prison, I know how broken our criminal justice system has become. Prison is important, but it should be reserved for those who commit the most serious crimes and for those who present a danger to society. We must look to other European countries, such as the Netherlands, that have managed to reduce their crime rate and their prison population simultaneously. To achieve this, as part of a number of policy changes, the Netherlands introduced milder sentencing tariffs, including a maximum sentence of six years for domestic burglary, in comparison to the UK's maximum of 14 years. At the same time, the Netherlands has made in-patient psychological treatment and drug and alcohol support available for all offenders. This is a prime example of successful policy-making that does not rely on simply locking people up for longer. Yes, people who commit crime should be punished, but we must use prison for the right reasons. If we do not, we will fail to make the lasting impact on crime and reoffending rates that the public deserve.